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M.2 Form Factor and M.2 Solid State Drives


M.2 is a new Form Factor used for expansion cards and connectors that are internally mounted into a computer. The M.2 connector interfaces with PCI Express 3.0+, SATA, and USB 3.0 technologies, providing manufacturers the ability to use the M.2 Module for Wireless Adapters, Bluetooth, and Solid State Drive integration.

M.2 Modules vary both in sizes and their connector's keying:

M.2 Module Sizes

M.2 Cards and Motherboard slots vary in sizes, both in the width and length of the card. Compatibility will depend in part with a Motherboard's ability to fit that specific card's size, in the same way other PCIe devices do. The current available sizes for M.2 modules are as follow:

  • Widths: 12, 16, 22, and 30 mm
  • Lengths: 16, 26, 30, 38, 42, 60, 80, and 110 mm

Commercially available M.2 modules are 22 mm wide with varying lengths of 30, 42, 60, 80, and 110 mm. Module dimensions will normally be displayed in the module's model. For example, a M.2 SATA 2280 SSD would indicate that the M.2 module is 22 mm in width and 80 mm in length. Currently Western Digital offers SSD with M.2 SATA 2280 form factor and M.2 NVMe 2230, 2280.


M.2 Module Keying Structure

By having several Notched pins, M.2 Modules can be easily fit into a mating connector, further enhancing easy compatibility. Specific Notched pins correspond to a unique Key, ranging from A (having pins 8-15 notched) to M (having pins 59-66 notched). Typical M.2 SSD keying structure includes B key, M key or B+M Key. For Western Digital M.2 SSDs, the keys used are B and M (B+M) on WD Green SATA and WD Blue SSD models, while the WD_BLACK uses only the M key.


M.2 SSD Protocol

M.2 Module offers various protocols to the attached component. For Solid State Drives, currently there are two widely used protocols: SATA and NVMe. Before purchasing an M.2 SSD, please check with the motherboard or computer manufacturer for M.2 connector compatibility.

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Answer ID 15539
Published 08/20/2018 02:12 AM
Updated 10/07/2023 02:43 PM

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